Implications of CaCl₂ application to plants in LID facilities

Low impact development (LID) technologies mimic the natural water cycle through the physico-chemical and biological interactions of plants, filter media and soil, and microorganisms, thereby reducing the release of pollutants. In LID facilities, plants carry out photosynthesis, facilitate microbial growth, and uptake pollutants contained in stormwater runoff. However, de-icers (CaCl₂) used to melt snow during winter slow the growth of plants and even increase plant mortality. In addition, de-icers change the soil structure, causing changes in soil content and affecting the growth of plants and microorganisms. Therefore, this study examined the effects of CaCl₂ on the resistance of plants, the removal efficiency of non-point source pollutants, and water circulation. The mortality rate of the tree and shrubs caused by CaCl₂ was found to be in the order of Rhododendron indicum > Spiraea prunifolia var. simpliciflora > Metasequoia glyptostroboides. For herbaceous plants, mortality rate was in the order of Pratia pedunculata > Aquilegia japonica > Tagetes erecta > Sedum makinoi aurea > Hosta longipes > Dianthus chinensis > Acorus gramineus > Liriope platyphylla. In addition, it was found that the amount of chlorophyll decreases with high concentrations of CaCl₂. The findings of this research will be useful for plant selection considering CaCl₂ concentrations applied to paved areas during the winter.